Healing of fractured bones treated by internal fixation depends on blood supply, which is provided to bone by both endosteal and periosteal routes. Both can be damaged in the fracture event, but also later, by the treatment. Conventional plates present a particularly high risk to the periosteal blood supply since they are made to fit the bone as closely as possible and then screwed tightly onto the bone. This kills the periosteum, and the bone, which needs it for its blood supply. Dead bone cannot heal and it presents a particularly high risk of infection. Through remodelling, bone can be restored, but seldom to its original shape and mechanical properties.
Many different plates, which reduce the area of contact to the bone, have been introduced to clinical use during the past two decades. Related to these developments are also different solutions to stably connect, or lock, bone screws and the plates. As the contact between the plate and the bone is reduced to very small areas, locking the screws becomes imperative—conventional screws, which are anchored in bone and compress the plate to the bone could produce contact pressures in excess of bone compressive strength. This would compromise stability of the construct and hence the process of fracture healing.